Florida is the nation`s boat theft capital and the problem is getting worse. The value of stolen vessels and motors has increased almost 50 percent in three years, from $17.8 million to $26.3 million.

Nowhere is the problem worse than the Gold Coast. In 1986, $7.1 million in vessels and motors were stolen in Dade County, $3.3 million in Broward, $2.1 million in Monroe and $2 million in Palm Beach.

``No boat is safe from theft,`` said Thomas `Motorboat` Wade, a convicted boat thief who worked locally and along the Gulf Coast.

Wade, who stole an estimated $10 million worth of boats before being sent to federal prison in 1982, is one of the few to get caught.

``There is almost no danger in stealing boats,`` McGillis said. ``Boat theft is a high profit, low-risk profession.``

Authorities say there are three reasons for this:

-- Boats can be easily registered without proof of ownership. Only 21 states, including Florida, require titles for boats.

-- Authorities lack interest and knowledge about boats.

-- The marine industry has failed to affix uniform serial numbers throughout the craft, making it hard to trace stolen vessels.

``We`re talking about one of the major problems facing the marine community,`` said Richard Briggs, director of the Marine Council, a group of 450 organizations and individuals that is sponsoring a national symposium on boat theft Tuesday at the Biscayne Bay Marriott in Miami.

National crime computers currently list more than 4,000 unsolved boat thefts in Florida, compared with 3,303 in Texas, 2,086 in California and 1,140 in South Carolina.

But authorities believe less than half the stolen boats are registered in state and national computers.

Officers either don`t bother to file the theft in the computers or they aren`t properly trained to read the identification numbers, or know what the equipment on a boat is called.

The rich aren`t the only victims of boat theft. More than 86 percent of the boats stolen in Florida are 20 feet long or less, according to the marine patrol.

``We`re talking about a problem that affects everybody in the water, whether they are a victim or through increased insurance rates. It`s mom and pop with the weekend fishing boat that`s getting ripped off,`` McGillis said.

Boats are being stolen from back yards. Maj. Kenneth Clark, the marine patrol commander in charge of Broward and Dade enforcement, came back from making a speech about boat theft recently and found his 16-foot boat missing from his fenced back yard in South Dade.

Boats are being taken from docks. A 46-foot Morgan ketch, the $124,000 Witch Craft II, was stolen from the Pier 66 marina in Fort Lauderdale and turned up four years later in Brazil.

Boats are being looted at night by teams of divers, who swim up to vessels and crawl aboard to steal.

``You take a radio from a car and you`re talking a couple hundred bucks. You steal a Loran (long-range navigational system) from a boat, and you could get $3,000 or $4,000,`` said marine officer David King.

King, who recovered a record 20 vessels in June during patrols of Broward and Dade, said there is evidence that car theft rings are stealing boats.

Wade was part of such a ring, stealing one boat a month for 10 years until he was caught in Louisiana because he overlooked an ID number hidden inside a depth sounder on a 45-foot cruiser. He spent three years in Seagoville federal penitentiary near Dallas for interstate transportation of stolen property.

The growing theft rate is fostered by loose registration laws and lack of ownership titles in most states. In many places, a thief can draw up his own bills of sale and get a boat title or registration at the county courthouse.

``While in prison, I titled 40 boats by mail just to prove how lax the system is,`` Wade said. ``Nothing has changed since then.``

Tightening the registration and title laws would be a major step against boat theft, McGillis said.

In addition, McGillis and others in the fight are continuously urging manufacturers to develop a uniform identification system. Currently, each of the 9,000 American vessel manufacturers uses a different system of numbers and letters, making it extremely hard to track stolen boats.

Manufacturers also are being encouraged to place hidden ID numbers in various places on the craft, similiar to the hidden numbers on cars, but the huge number of boat builders makes this job difficult. Boats must have a visible number on the hull, but this can be sanded until no trace of the original ID remains.